1. Field of the Invention
This invention relates to a crew member detecting device which detects whether or not a crew member is on the bucket seat, for instance, in a vehicle.
2. Description of the Prior Art
Prior to the description of a crew member detecting device of the invention, a vehicle crew member protecting device such as an air bag device will be described with reference to FIG. 1.
FIG. 1 shows a vehicle crew member protecting device which is to inflate air bags for both the driver's bucket seat and assistant driver's bucket seat in a vehicle when an accident occurs. When a collision occurs in a front-to-rear or rear-to-front direction of the vehicle, a sensor 1 applies an acceleration signal to an air bag inflation decision control circuit 2, where the degree of the accident is determined according to the magnitude and the duration time of the acceleration signal. When the circuit 2 determines that the accident is serious (damaging the crew members greatly), it applies an ignition current to a first squib 3 for the driver's bucket seat to inflate the driver's bucket seat air bag, and operates an inflation timing control circuit 4 to ignite second and third squibs 5 and 6 for the assistant driver's bucket seat at different time instants, to inflate driver's bucket seat air bags.
However, the vehicle crew member protecting device thus organized is disadvantageous in the following points: This is, a collision may occur even when the vehicle is traveling without a assistant driver. In this case, too, the device will operate; this is, the ignition currents are applied to all the first, second and third squibs 3, 5 and 6. Hence, in the case where the device is repaired so that the vehicle is used again, the repair work is not accomplished merely by replacing parts of the vehicle crew member protecting device; that is, the latter must be replaced in its entirety. Hence, the repair cost is relatively high.
In USA, some of the insurance companies decrease a premium for a vehicle which is so designed that, in such a case, the vehicle crew member protecting device can be repaired by replacing some of the parts. Hence, in Japan, too, the recent technical tendency of the vehicle crew member protecting device is such that, in the case where no crew member is on the assistant driver's bucket seat, the air bag for the assistant driver's bucket seat is not inflated. In this connection, what is provided is a switch which is turned on when a person sits on the assistant driver's bucket seat, namely, a mechanical sit-on switch, or a sheet-shaped switch board. However, since the switch is operated by a load applied thereto, it gives rise to another problem that it is operated not only when a person sits on it but also a piece of baggage is set on it.